A polyolefin composition

ABSTRACT

The instant invention provides a polyolefin composition suitable for injection molding applications, and method of making such injection molded articles. The polyolefin composition suitable for injection molding applications comprises: an ethylene/α-olefin interpolymer composition comprising: (a) from 25 to 50 percent by weight of a first ethylene/α-olefin copolymer fraction having a density in the range of from 0.924 to 0.937 g/cm 3 , a melt index (I 2 ) in the range of from 0.03 to 0.3 g/10 min, (b) from 50 to 75 percent by weight of a second ethylene homopolymer fraction having a density in the range of from greater than 0.960 g/cm 3 , a melt index (I 2 ) in the range of from 100 to 180 g/10 minutes, wherein said ethylene/α-olefin interpolymer composition has a density in the range of from 0.950 to 0.958 g/cm 3 , a melt index (I 2 ) in the range of from 1.0 g/10 min to 3.5 g/10 min, a zero shear viscosity ratio (ZSVR) in the range of from 1.01 to 2.5, a molecular weight distribution (M w /M n ) in the range of from 2.0 to 4.0, and tan delta at 0.1 radian/second and 190° C. in the range of from 9 to 50.

REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 61/746,151, filed on Dec. 27, 2012.

FIELD OF INVENTION

The instant invention relates to a polyolefin composition suitable forinjection molding or compression molding applications, and method ofproducing the same.

BACKGROUND OF THE INVENTION

The use of polymeric materials to manufacture molded articles, such asclosure devices and containers, is generally known. Different methodsmay be employed to manufacture closure devices, such as bottle caps, orcontainers, such as bottles. For example, such closure devices may bemanufactured via compression molding or injection molding processes; orin the alternative, containers may be manufactured via blow molding,injection blow molding, or injection stretch blow molding.

In compression molding process, a two-piece mold provides a cavityhaving the shape of a desired molded article. The mold is heated. Anappropriate amount of molten molding compound from an extruder is loadedinto the lower half of the mold. The two parts of the mold are broughttogether under pressure. The molding compound, softened by heat, isthereby welded into a continuous mass having the shape of the cavity. Ifthe molding compound is a thermosetting material, the continuous massmay be hardened via further heating, under pressure, in the mold. If themolding compound is a thermoplastic material, the continuous mass may behardened via chilling, under pressure, in the mold.

In injection molding process, molding compound is fed into an extrudervia a hopper. The extruder conveys, heats, melts, and pressurizes themolding compound to a form a molten stream. The molten stream is forcedout of the extruder through a nozzle into a relatively cool mold heldclosed under pressure thereby filing the mold. The melt cools andhardens until fully set-up. The mold then opens and the molded part isremoved.

In blow molding process, for example injection blow molding, the moldingcompound is melted, and then, it is formed into a tube or parison. Theends of the tube or parison is sealed, except for an area in which theblowing air can enter. The sealed tube or parison is inflated inside ofa mold thereby taking the shape of the mold. The molded article iscooled, and then ejected from the mold. If necessary, the molded articleis then trimmed.

In general, a closure device, such as a soda bottle cap, should bestrong enough to withstand the pressure, e.g. of a carbonated drink, andyet soft enough to provide an excellent seal on the bottle without theneed for an inner liner. Additionally, a closure device, such as a sodabottle cap, should generally possess good environmental stress crackresistance, good impact strength, good removal torque, and good striptorque. Different techniques have been employed to provide for suchclosure devices having acceptable properties.

For example, the use of a polypropylene polymer as a bottle cap closurefor the needed strength with an inner liner, which may be comprised ofsoft ethylene/vinyl acetate (EVA), polyvinyl chloride (PVC), butylrubber, etc., is also generally well known. However, this two-partconstruction is costly because of the need for an inner liner.Furthermore, it would be easier and more convenient to use a one-piececlosure, without a liner.

In attempts to eliminate the need for a two-part cap construction, theuse of different blends of polymers has been suggested. However, thereis still a need for polymer composition that can be molded into closuredevices having acceptable properties, such as no need for liners tofacilitate a seal, acceptable taste and odor, satisfactory stress crackresistance, and impact strength to prevent cap failure.

SUMMARY OF THE INVENTION

The instant invention provides a polyolefin composition suitable forinjection molding applications, and method of making such injectionmolded articles.

In one embodiment, the instant invention provides a polyolefincomposition suitable for injection molding applications comprising: anethylene/α-olefin interpolymer composition comprising: (a) from 25 to 50percent by weight of a first ethylene/α-olefin copolymer fraction havinga density in the range of from 0.924 to 0.937 g/cm³, a melt index (I₂)in the range of from 0.03 to 0.3 g/10 min, (b) from 50 to 75 percent byweight of a second ethylene homopolymer fraction having a density in therange of from greater than 0.960 g/cm³, a melt index (I₂) in the rangeof from 100 to 180 g/10 minutes, wherein said ethylene/α-olefininterpolymer composition has a density in the range of from 0.950 to0.958 g/cm³, a melt index (I₂) in the range of from 1.0 g/10 min to 3.5g/10 min, a zero shear viscosity ratio (ZSVR) in the range of from 1.01to 2.5, a molecular weight distribution (M_(w)/M_(n)) in the range offrom 2.0 to 4.0, and tan delta at 0.1 radian/second and 190° C. in therange of from 9 to 50, wherein said ethylene/α-olefin interpolymercomposition has at least 1 peak on elution profile via crystallizationelution fractionation (CEF) procedure, wherein said peak comprises atleast 95 weight percent of the total area of the elution profile,wherein said elution temperature peak is at an elution temperaturegreater than 95° C., and wherein the width of the elution temperaturepeak at 50 percent peak height is greater than 4° C. and less than 6°C., and wherein the standard deviation of the temperature is less than6° C.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form that is exemplary; it being understood, however, thatthis invention is not limited to the precise arrangements andinstrumentalities shown.

FIG. 1 illustrates the elution profile via crystallization elutionfractionation (CEF) procedure for Inventive Examples and ComparativeExamples.

DETAILED DESCRIPTION OF THE INVENTION

The instant invention provides a polyolefin composition suitable forinjection molding applications, and method of making such injectionmolded articles.

In one embodiment, the instant invention provides a polyolefincomposition suitable for injection molding applications comprising: anethylene/α-olefin interpolymer composition comprising: (a) from 25 to 50percent by weight of a first ethylene/α-olefin copolymer fraction havinga density in the range of from 0.924 to 0.937 g/cm³, a melt index (I₂)in the range of from 0.03 to 0.3 g/10 min, (b) from 50 to 75 percent byweight of a second ethylene homopolymer fraction having a density in therange of from greater than 0.960 g/cm³, a melt index (I₂) in the rangeof from 100 to 180 g/10 minutes, wherein said ethylene/α-olefininterpolymer composition has a density in the range of from 0.950 to0.958 g/cm³, a melt index (I₂) in the range of from 1.0 g/10 min to 3.5g/10 min, a zero shear viscosity ratio (ZSVR) in the range of from 1.01to 2.5, a molecular weight distribution (M_(w)/M_(n)) in the range offrom 2.0 to 4.0, and tan delta at 0.1 radian/second and 190° C. in therange of from 9 to 50, wherein said ethylene/α-olefin interpolymercomposition has at least 1 peak on elution profile via crystallizationelution fractionation (CEF) procedure, wherein said peak comprises atleast 95 weight percent of the total area of the elution profile,wherein said elution temperature peak is at an elution temperaturegreater than 95° C., and wherein the width of the elution temperaturepeak at 50 percent peak height is greater than 4° C. and less than 6°C., and wherein the standard deviation of the temperature is less than6° C.

The polyolefin composition may further comprise additional componentssuch as one or more other polymers. For example the polyolefincomposition may further comprise one or more ethylene polymers, or oneor more propylene based polymers, or combinations thereof.

In one embodiment, one or more ethylene/α-olefin interpolymercompositions and one or more propylene/α-olefin interpolymercompositions, as described herein, may be blended via any method knownto a person of ordinary skill in the art including, but not limited to,dry blending, and melt blending via any suitable equipment, for example,an extruder, to produce the inventive injection molding composition.

The polyolefin composition may further comprise additional componentssuch as one or more additives. Such additives include, but are notlimited to, antistatic agents, color enhancers, dyes, lubricants,fillers such as TiO₂ or CaCO₃, opacifiers, nucleators, pigments, primaryanti-oxidants, secondary anti-oxidants, processing aids, UV stabilizers,anti-blocks, slip agents, tackifiers, fire retardants, anti-microbialagents, odor reducer agents, anti-fungal agents, and combinationsthereof. The polyolefin composition may contain from about 0.01 to about10 percent by the combined weight of such additives, based on the weightof the ethylene-based polymer composition including such additives.

Ethylene/α-Olefin Interpolymer Composition

The ethylene/α-olefin interpolymer composition comprising: (a) from 25to 50 percent by weight of a first ethylene/α-olefin copolymer fractionhaving a density in the range of from 0.924 to 0.937 g/cm³, a melt index(I₂) in the range of from 0.03 to 0.3 g/10 min, (b) from 50 to 75percent by weight of a second ethylene homopolymer fraction having adensity in the range of from greater than 0.960 g/cm³, a melt index (I₂)in the range of from 100 to 180 g/10 minutes, wherein saidethylene/α-olefin interpolymer composition has a density in the range offrom 0.950 to 0.958 g/cm³, a melt index (I₂) in the range of from 1.0g/10 min to 3.5 g/10 min, a zero shear viscosity ratio (ZSVR) in therange of from 1.01 to 2.5, a molecular weight distribution (M_(w)/M_(n))in the range of from 2.0 to 4.0, and tan delta at 0.1 radian/second and190° C. in the range of from 9 to 50, wherein said ethylene/α-olefininterpolymer composition has at least 1 peak on elution profile viacrystallization elution fractionation (CEF) procedure, wherein said peakcomprises at least 95 weight percent of the total area of the elutionprofile, wherein said elution temperature peak is at an elutiontemperature greater than 95° C., and wherein the width of the elutiontemperature peak at 50 percent peak height is greater than 4° C. andless than 6° C., and wherein the standard deviation of the temperatureis less than 6° C.

The ethylene/α-olefin interpolymer composition is further characterizedby one or more of the followings:

-   -   a. has a vinyl unsaturation of less than 0.15 vinyls per one        thousand carbon atoms present in the backbone of the        ethylene/α-olefin interpolymer composition; and/or    -   b. has a tan delta at 0.1 radian/second, determined at 190° C.,        in the range of from 9 to 50;    -   c. has Comonomer Distribution Constant (CDC) in the range of        from 150 or less;    -   d. has a environmental stress crack resistance (ESCR) failure        time F50 of at least 150 hours, determined by ASTM 1693 Method B        in aqueous 10% Igepal; and/or    -   e. has a oligomers content, i.e. C₁₀-C₄₄, of less than 100 ppm.

The ethylene/α-olefin interpolymer composition comprises (a) less thanor equal to 100 percent, for example, at least 70 percent, or at least80 percent, or at least 90 percent, of the units derived from ethylene;and (b) less than 30 percent, for example, less than 25 percent, or lessthan 20 percent, or less than 10 percent, by weight of units derivedfrom one or more α-olefin comonomers. The term “ethylene/α-olefininterpolymer composition” refers to a polymer that contains more than 50mole percent polymerized ethylene monomer (based on the total amount ofpolymerizable monomers) and, optionally, may contain at least onecomonomer.

The α-olefin comonomers typically have no more than 20 carbon atoms. Forexample, the α-olefin comonomers may preferably have 3 to 10 carbonatoms, and more preferably 3 to 8 carbon atoms. Exemplary α-olefincomonomers include, but are not limited to, propylene, 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and4-methyl-1-pentene. The one or more α-olefin comonomers may, forexample, be selected from the group consisting of propylene, 1-butene,1-hexene, and 1-octene; or in the alternative, from the group consistingof 1-hexene and 1-octene.

The ethylene/α-olefin interpolymer composition is characterized byhaving a Comonomer Distribution Constant (CDC) in the range of from 150or less, for example from 75 to 150, or in the alternative, from 90 to135.

The ethylene-based polymer composition is characterized by having a zeroshear viscosity ratio (ZSVR) in the range of from 1.01 to 2.5, forexample from 1.15 to 2.5, or in the alternative from 1.15 to 2.0, or inthe alternative from 1.2 to 1.8.

The ethylene/α-olefin interpolymer composition is characterized byhaving a tan delta at 0.1 radian/second, determined at 190° C., in therange of from 9 to 50, for example from 9 to 40, or from 9 to 30, orfrom 9 to 25, or from 10 to 25, or from 10 to 30, or from 10 to 40. Theethylene/α-olefin interpolymer composition has a density in the range of0.950 to 0.958 g/cm³, for example from 0.950 to 0.956 g/cm³. Forexample, the density can be from a lower limit of 0.950, 0.951, or 0.952g/cm³ to an upper limit of 0.955, 0.956, 0.957, or 0.958 g/cm³.

The ethylene/α-olefin interpolymer composition comprising from 25% to50% percent by weight, preferably from 30% to 45%, more preferably from33% to 43%, most preferably from 35% to 42% of the firstethylene/α-olefin copolymer fraction.

The first ethylene/α-olefin copolymer fraction has a density in therange of 0.924 to 0.937 g/cm³, for example from 0.925 to 0.936 g/cm³.For example, the density can be from a lower limit of 0.924, 0.925,0.926, or 0.927 g/cm³ to an upper limit of 0.934, 0.935, 0.936, or 0.937g/cm³.

The second ethylene/α-olefin homopolymer fraction has a density in therange of greater than 0.960 g/cm³. For example, the density can be fromgreater than 0.960, 0.963, 0.965, 0.967, 0.970 g/cm³. The density of thesecond ethylene/α-olefin homopolymer fraction can be approximated basedon the density of a polymer prepared in a single reactor under the samepolymerisation conditions of the second ethylene/α-olefin homopolymerfraction in the absence of the first ethylene/α-olefin copolymerfraction.

The ethylene/α-olefin interpolymer composition has a molecular weightdistribution (M_(w)/M_(n)) in the range of from 2.0 to 4.0. For example,the molecular weight distribution (M_(w)/M_(n)) can be from a lowerlimit of 2.0, 2.1, or 2.2 to an upper limit of 2.6, 2.8, 3.0, 3.5, or4.0.

The first ethylene/α-olefin copolymer fraction has a molecular weightdistribution (M_(w)/M_(n)) in the range of from 1.5 to 3.5, for examplefrom 2 to 3. For example, the molecular weight distribution(M_(w)/M_(n)) can be from a lower limit of 1.5, 1.7, 2.0, 2.1, or 2.2 toan upper limit of 2.5, 2.6, 2.8, 3.0, or 3.5.

The second ethylene/α-olefin homopolymer fraction has a molecular weightdistribution (M_(w)/M_(n)) in the range of from 1.5 to 3.0, for examplefrom 2 to 3. For example, the molecular weight distribution(M_(w)/M_(n)) can be from a lower limit of 1.5, 1.7, 2.0, 2.1, or 2.2 toan upper limit of 2.5, 2.6, 2.8, or 3.0.

The ethylene/α-olefin interpolymer composition has a melt index (I₂) (at190° C./2.16 kg) in the range of from 1.0 to 3.5 g/10 minutes, forexample from 1.5 to 3.0 g/10 minutes, or from 1.5 to 2.5 g/10 minutes.For example, the melt index (I₂ at 190° C./2.16 kg) can be from a lowerlimit of 1.0, 1.3, 1.5, or 1.7 g/10 minutes to an upper limit of 2.5,2.7, 3.0, 3.3, or 3.5 g/10 minutes.

The first ethylene/α-olefin copolymer fraction has a melt index (I₂) (at190° C./2.16 kg) in the range of from 0.03 to 0.3 g/10 minutes, forexample from 0.05 to 0.25 g/10 minutes, or from 0.05 to 0.2 g/10minutes, or from 0.05 to 0.15 g/10 minutes.

The ethylene/α-olefin interpolymer composition has vinyl unsaturation ofless than 0.15, for example equal or less than 0.12, or less than 0.1vinyls per one thousand carbon atoms present in the backbone of theethylene-based polymer composition.

The ethylene/α-olefin interpolymer composition may further compriseadditional components such as one or more additives. Such additivesinclude, but are not limited to, antistatic agents, color enhancers,dyes, lubricants, fillers such as TiO₂ or CaCO₃, opacifiers, nucleators,processing aids, pigments, primary anti-oxidants, secondaryanti-oxidants, processing aids, UV stabilizers, anti-blocks, slipagents, tackifiers, fire retardants, anti-microbial agents, odor reduceragents, anti-fungal agents, and combinations thereof. Theethylene/α-olefin interpolymer composition may contain from about 0.1 toabout 10 percent by the combined weight of such additives, based on theweight of the ethylene-based polymer composition including suchadditives.

In one embodiment, ethylene/α-olefin interpolymer composition has atleast 1 peak on elution profile via crystallization elutionfractionation (CEF) procedure, wherein said peak comprises at least 95weight percent of the total area of the elution profile, wherein saidelution temperature peak is at an elution temperature greater than 95°C., and wherein the width of the elution temperature peak at 50 percentpeak height is greater than 4° C. and less than 6° C., and wherein thestandard deviation of the temperature is less than 6° C.

Any conventional polymerization processes may be employed to produce theethylene/α-olefin interpolymer composition. Such conventionalpolymerization processes include, but are not limited to, solutionpolymerization process, using one or more conventional reactors e.g.loop reactors, isothermal reactors, stirred tank reactors, batchreactors in parallel, series, and/or any combinations thereof.

The ethylene/α-olefin interpolymer composition may, for example, beproduced via solution phase polymerization process using one or moreloop reactors, isothermal reactors, and combinations thereof.

In general, the solution phase polymerization process occurs in one ormore well-mixed reactors such as one or more isothermal loop reactors orone or more adiabatic reactors at a temperature in the range of from 115to 250° C.; for example, from 115 to 200° C., and at pressures in therange of from 300 to 1000 psi; for example, from 400 to 750 psi. In oneembodiment in a dual reactor, the temperature in the first reactor is inthe range of from 115 to 190° C., for example, from 115 to 150° C., andthe second reactor temperature is in the range of 150 to 250° C., forexample, from 170 to 225° C. In another embodiment in a single reactor,the temperature in the reactor is in the range of from 115 to 250° C.,for example, from 115 to 225° C. The residence time in solution phasepolymerization process is typically in the range of from 2 to 30minutes; for example, from 10 to 20 minutes. Ethylene, solvent,hydrogen, one or more catalyst systems, optionally one or morecocatalysts, and optionally one or more comonomers are fed continuouslyto one or more reactors. Exemplary solvents include, but are not limitedto, isoparaffins. For example, such solvents are commercially availableunder the name ISOPAR E from ExxonMobil Chemical Co., Houston, Tex. Theresultant mixture of the ethylene/alpha-olefin interpolymer and solventis then removed from the reactor and the ethylene/alpha-olefininterpolymer is isolated. Solvent is typically recovered via a solventrecovery unit, i.e. heat exchangers and vapor liquid separator drum, andis then recycled back into the polymerization system.

In one embodiment, the ethylene/α-olefin interpolymer composition may beproduced via solution polymerization in a dual reactor system, forexample a dual loop reactor system, wherein ethylene and optionally oneor more α-olefins are polymerized in the presence of one or morecatalyst systems. Additionally, one or more cocatalysts may be present.

In another embodiment, the ethylene/alpha-olefin interpolymers may beproduced via solution polymerization in a single reactor system, forexample a single loop reactor system, wherein ethylene and optionallyone or more α-olefins are polymerized in the presence of one or morecatalyst systems.

An exemplary catalyst system suitable for producing the first ethylene/aolefin interpolymer can be a catalyst system comprising a procatalystcomponent comprising a metal-ligand complex of formula (IA):

wherein:

M is titanium, zirconium, or hafnium, each independently being in aformal oxidation state of +2, +3, or +4; and

n is an integer of from 0 to 3, and wherein when n is 0, X is absent;and

Each X independently is a monodentate ligand that is neutral,monoanionic, or dianionic; or two Xs are taken together to form abidentate ligand that is neutral, monoanionic, or dianionic; and

X and n are chosen in such a way that the metal-ligand complex offormula (IA) is, overall, neutral; and

Each Z independently is O, S, N(C₁-C₄₀)hydrocarbyl, orP(C₁-C₄₀)hydrocarbyl; and

The Z-L-Z fragment is comprised of formula (II):

R¹⁻¹⁶ are selected from the group consisting of a (C₁-C₄₀)hydrocarbyl,(C₁-C₄₀)heterohydrocarbyl, Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)—, halogen atom,hydrogen atom, and combination thereof.

Optionally two or more R groups (from R⁹⁻¹³ or R⁴⁻⁸) can combinetogether into ring structures, with such ring structures having from 3to 50 atoms in the ring excluding any hydrogen atoms.

Each of the aryl, heteroaryl, hydrocarbyl, heterohydrocarbyl,Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂, OR^(C), SR^(C),R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—, R^(C)C(O)O—, R^(C)OC(O)—,R^(C)C(O)N(R)—, (R^(C))₂NC(O)—, hydrocarbylene, and heterohydrocarbylenegroups independently is unsubstituted or substituted with one or moreR^(S) substituents; and Each R^(S) independently is a halogen atom,polyfluoro substitution, perfluoro substitution, unsubstituted(C₁-C₁₈)alkyl, F₃C—, FCH₂O—, F₂HCO—, F₃CO—, R₃Si—, R₃Ge—, RO—, RS—,RS(O)—, RS(O)₂—, R₂P—, R₂N—, R₂C═N—, NC—, RC(O)O—, ROC(O)—, RC(O)N(R)—,or R₂NC(O)—, or two of the R^(S) are taken together to form anunsubstituted (C₁-C₁₈)alkylene, wherein each R independently is anunsubstituted (C₁-C₁₈)alkyl.

In one embodiment the catalyst system suitable for producing the firstethylene/a olefin interpolymer can be a catalyst system comprisingbis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethyl)-methylene-1,2-cyclohexanediylhafnium(IV) dimethyl, represented by the following formula:

An exemplary catalyst system suitable for producing the secondethylene/a olefin homopolymer can be a catalyst system comprising aprocatalyst component comprising a metal-ligand complex of formula (IB):

wherein:

M is titanium, zirconium, or hafnium, each independently being in aformal oxidation state of +2, +3, or +4; and

n is an integer of from 0 to 3, and wherein when n is 0, X is absent;and

Each X independently is a monodentate ligand that is neutral,monoanionic, or dianionic; or two Xs are taken together to form abidentate ligand that is neutral, monoanionic, or dianionic; and

X and n are chosen in such a way that the metal-ligand complex offormula (IB) is, overall, neutral; and

Each Z independently is O, S, N(C₁-C₄₀)hydrocarbyl, orP(C₁-C₄₀)hydrocarbyl; and

L is (C₃-C₄₀)hydrocarbylene or (C₃-C₄₀)heterohydrocarbylene, wherein the(C₃-C₄₀)hydrocarbylene has a portion that comprises a 3-carbon atom to10-carbon atom linker backbone linking the Z atoms in formula (IB) (towhich L is bonded) and the (C₃-C₄₀)heterohydrocarbylene has a portionthat comprises a 3-atom to 10-atom linker backbone linking the Z atomsin formula (IB), wherein each of the from 3 to 10 atoms of the 3-atom to10-atom linker backbone of the (C₃-C₄₀)heterohydrocarbyleneindependently is a carbon atom or heteroatom, wherein each heteroatomindependently is O, S, S(O), S(O)₂, Si(R^(C))₂, Ge(R^(C))₂, P(R^(P)), orN(R^(N)), wherein independently each R^(C) is (C₁-C₃₀)hydrocarbyl, eachR^(P) is (C₁-C₃₀)hydrocarbyl; and each R^(N) is (C₁-C₃₀)hydrocarbyl orabsent; and

R¹, R¹⁶, or both comprise of formula (III), and preferably R¹ and R¹⁶are the same; and

R¹⁻²⁴ are selected from the group consisting of a (C₁-C₄₀)hydrocarbyl,(C₁-C₄₀)heterohydrocarbyl, Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)—, halogen atom,hydrogen atom, and combination thereof.

When R²² is H, then R¹⁹ is a (C₁-C₄₀)hydrocarbyl;(C₁-C₄₀)heterohydrocarbyl; Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)— or halogenatom; and

When R¹⁹ is H, then R²² is a (C₁-C₄₀)hydrocarbyl;(C₁-C₄₀)heterohydrocarbyl; Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)— or halogenatom; and

Preferably, R²² and R¹⁹ are both a (C₁-C₄₀)hydrocarbyl;(C₁-C₄₀)heterohydrocarbyl; Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)— or halogenatom; and

When R⁸ is H, then R⁹ is a (C₁-C₄₀)hydrocarbyl;(C₁-C₄₀)heterohydrocarbyl; Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)— or halogenatom; and When R⁹ is H, then R⁸ is a (C₁-C₄₀)hydrocarbyl;(C₁-C₄₀)heterohydrocarbyl; Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)— or halogenatom; and

Preferably, R₈ and R₉ are both a (C₁-C₄₀)hydrocarbyl;(C₁-C₄₀)heterohydrocarbyl; Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂,OR^(C), SR^(C), NO₂, CN, CF₃, R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—,R^(C)C(O)O—, R^(C)OC(O)—, R^(C)C(O)N(R)—, (R^(C))₂NC(O)— or halogenatom; and

Optionally two or more R groups (from R⁹⁻¹³ or R⁴⁻⁸) can combinetogether into ring structures, with such ring structures having from 3to 50 atoms in the ring excluding any hydrogen atoms.

Each of the aryl, heteroaryl, hydrocarbyl, heterohydrocarbyl,Si(R^(C))₃, Ge(R^(C))₃, P(R^(P))₂, N(R^(N))₂, OR^(C), SR^(C),R^(C)S(O)—, R^(C)S(O)₂—, (R^(C))₂C═N—, R^(C)C(O)O—, R^(C)OC(O)—,R^(C)C(O)N(R)—, (R^(C))₂NC(O)—, hydrocarbylene, and heterohydrocarbylenegroups independently is unsubstituted or substituted with one or moreR^(S) substituents; and

Each R^(S) independently is a halogen atom, polyfluoro substitution,perfluoro substitution, unsubstituted (C₁-C₁₈)alkyl, F₃C—, FCH₂O—,F₂HCO—, F₃CO—, R₃Si—, R₃Ge—, RO—, RS—, RS(O)—, RS(O)₂—, R₂P—, R₂N—,R₂C═N—, NC—, RC(O)O—, ROC(O)—, RC(O)N(R)—, or R₂NC(O)—, or two of theR^(S) are taken together to form an unsubstituted (C₁-C₁₈)alkylene,wherein each R independently is an unsubstituted (C₁-C₁₈)alkyl.

Optionally two or more R groups (from R²⁰⁻²⁴) can combine together intoring structures, with such ring structures having from 3 to 50 atoms inthe ring excluding any hydrogen atoms.

In one embodiment the catalyst system suitable for producing the secondethylene/a olefin homopolymer can be a catalyst system comprising((3-(2,7-di-tert-butyl-9H-carbazol-9-yl)-2′-(3-((3′-(2,7-di-tert-butyl-9H-carbazol-9-yl)-5-fluoro-2′-hydroxy-3-methyl-5′-(2,4,4-trimethylpentan-2-yl)-[1,1′-biphenyl]-2-yl)oxy)propoxy)-5′-fluoro-3′-methyl-5-(2,4,4-trimethylpentan-2-yl)-[1,1′-biphenyl]-2-yl)oxy)hafnium(IV) dimethyl, represented by the following formula:

Co-Catalyst Component

The above described catalyst systems can be rendered catalyticallyactive by contacting it to, or combining it with, the activatingco-catalyst or by using an activating technique such as those that areknown in the art for use with metal-based olefin polymerizationreactions. Suitable activating co-catalysts for use herein include alkylaluminums; polymeric or oligomeric alumoxanes (also known asaluminoxanes); neutral Lewis acids; and non-polymeric, noncoordinating,ion-forming compounds (including the use of such compounds underoxidizing conditions). A suitable activating technique is bulkelectrolysis. Combinations of one or more of the foregoing activatingco-catalysts and techniques are also contemplated. The term “alkylaluminum” means a monoalkyl aluminum dihydride or monoalkylaluminumdihalide, a dialkyl aluminum hydride or dialkyl aluminum halide, or atrialkylaluminum. Aluminoxanes and their preparations are known at, forexample, United States patent number (USPN) U.S. Pat. No. 6,103,657.Examples of preferred polymeric or oligomeric alumoxanes aremethylalumoxane, triisobutylaluminum-modified methylalumoxane, andisobutylalumoxane.

Exemplary Lewis acid activating co-catalysts are Group 13 metalcompounds containing from 1 to 3 hydrocarbyl substituents as describedherein. In some embodiments, exemplary Group 13 metal compounds aretri(hydrocarbyl)-substituted-aluminum or tri(hydrocarbyl)-boroncompounds. In some other embodiments, exemplary Group 13 metal compoundsare tri(hydrocarbyl)-substituted-aluminum or tri(hydrocarbyl)-boroncompounds are tri((C₁-C₁₀)alkyl)aluminum or tri((C₆-C₁₈)aryl)boroncompounds and halogenated (including perhalogenated) derivativesthereof. In some other embodiments, exemplary Group 13 metal compoundsare tris(fluoro-substituted phenyl)boranes, in other embodiments,tris(pentafluorophenyl)borane. In some embodiments, the activatingco-catalyst is a tris((C₁-C₂₀)hydrocarbyl) borate (e.g., trityltetrafluoroborate) or a tri((C₁-C₂₀)hydrocarbyl)ammoniumtetra((C₁-C₂₀)hydrocarbyl)borane (e.g., bis(octadecyl)methylammoniumtetrakis(pentafluorophenyl)borane). As used herein, the term “ammonium”means a nitrogen cation that is a ((C₁-C₂₀)hydrocarbyl)₄N⁺, a((C₁-C₂₀)hydrocarbyl)₃N(H)⁺, a ((C₁-C₂₀)hydrocarbyl)₂N(H)₂ ⁺,(C₁-C₂₀)hydrocarbylN(H)₃ ⁺, or N(H)₄ ⁺, wherein each (C₁-C₂₀)hydrocarbylmay be the same or different.

Exemplary combinations of neutral Lewis acid activating co-catalystsinclude mixtures comprising a combination of a tri((C₁-C₄)alkyl)aluminumand a halogenated tri((C₆-C₁₈)aryl)boron compound, especially atris(pentafluorophenyl)borane. Other exemplary embodiments arecombinations of such neutral Lewis acid mixtures with a polymeric oroligomeric alumoxane, and combinations of a single neutral Lewis acid,especially tris(pentafluorophenyl)borane with a polymeric or oligomericalumoxane. Exemplary embodiments ratios of numbers of moles of(metal-ligand complex):(tris(pentafluoro-phenylborane): (alumoxane)[e.g., (Group 4 metal-ligandcomplex):(tris(pentafluoro-phenylborane):(alumoxane)] are from 1:1:1 to1:10:30, other exemplary embodiments are from 1:1:1.5 to 1:5:10.

Many activating co-catalysts and activating techniques have beenpreviously taught with respect to different metal-ligand complexes inthe following USPNs: U.S. Pat. No. 5,064,802; U.S. Pat. No. 5,153,157;U.S. Pat. No. 5,296,433; U.S. Pat. No. 5,321,106; U.S. Pat. No.5,350,723; U.S. Pat. No. 5,425,872; U.S. Pat. No. 5,625,087; U.S. Pat.No. 5,721,185; U.S. Pat. No. 5,783,512; U.S. Pat. No. 5,883,204; U.S.Pat. No. 5,919,983; U.S. Pat. No. 6,696,379; and U.S. Pat. No.7,163,907. Examples of suitable hydrocarbyloxides are disclosed in U.S.Pat. No. 5,296,433. Examples of suitable Bronsted acid salts foraddition polymerization catalysts are disclosed in U.S. Pat. No.5,064,802; U.S. Pat. No. 5,919,983; U.S. Pat. No. 5,783,512. Examples ofsuitable salts of a cationic oxidizing agent and a noncoordinating,compatible anion as activating co-catalysts for addition polymerizationcatalysts are disclosed in U.S. Pat. No. 5,321,106. Examples of suitablecarbenium salts as activating co-catalysts for addition polymerizationcatalysts are disclosed in U.S. Pat. No. 5,350,723. Examples of suitablesilylium salts as activating co-catalysts for addition polymerizationcatalysts are disclosed in U.S. Pat. No. 5,625,087. Examples of suitablecomplexes of alcohols, mercaptans, silanols, and oximes withtris(pentafluorophenyl)borane are disclosed in U.S. Pat. No. 5,296,433.Some of these catalysts are also described in a portion of U.S. Pat. No.6,515,155 B1 beginning at column 50, at line 39, and going throughcolumn 56, at line 55, only the portion of which is incorporated byreference herein.

In some embodiments, the above described catalyst systems can beactivated to form an active catalyst composition by combination with oneor more cocatalyst such as a cation forming cocatalyst, a strong Lewisacid, or a combination thereof. Suitable cocatalysts for use includepolymeric or oligomeric aluminoxanes, especially methyl aluminoxane, aswell as inert, compatible, noncoordinating, ion forming compounds.Exemplary suitable cocatalysts include, but are not limited to modifiedmethyl aluminoxane (MMAO), bis(hydrogenated tallow alkyl)methyl,tetrakis(pentafluorophenyl)borate(1-) amine (RIBS-2), triethyl aluminum(TEA), and any combinations thereof

In some embodiments, one or more of the foregoing activatingco-catalysts are used in combination with each other. An especiallypreferred combination is a mixture of a tri((C₁-C₄)hydrocarbyl)aluminum,tri((C₁-C₄)hydrocarbyl)borane, or an ammonium borate with an oligomericor polymeric alumoxane compound.

End-Use Applications of the Polyolefin Composition

The polyolefin compositions according to the present invention may beused in injection molding applications.

In application, the inventive polyolefin composition may be used tomanufacture shaped articles. Such articles may include, but are notlimited to, closure devices such as bottle caps, or container devicessuch as bottles. Different methods may be employed to manufacturearticles such as bottle caps and bottles. Suitable conversion techniquesinclude, but are not limited to, injection molding, injection blowmolding, and/or injection stretch blow molding. Such techniques aregenerally well known.

In injection molding process, the inventive polyolefin composition isfed into an extruder via a hopper. The extruder conveys, heats, melts,and pressurizes the polyolefin composition to a form a molten stream.The molten stream is forced out of the extruder through a nozzle into arelatively cool mold held closed under pressure thereby filling themold. The melt cools and hardens until fully set-up. The mold then opensand the molded article, for example bottle cap, is removed. Theinjection molded cap may include a skirt that axially extends from theperiphery of a base, and may further include internal threads forsecuring the cap to a container.

Closure devices such as bottle caps including the inventive polyolefincomposition exhibit improved environmental crack resistance. Such bottlecaps are adapted to withstand the pressure of carbonated drinks. Suchbottle caps further facilitate closure, and sealing of a bottle, that isoptimum torque provided by a machine to screw the cap on the bottle, orunsealing a bottle, that is optimum torque provide by a person tounscrew the cap.

The polyolefin composition of the present invention provide improvedorganoleptic properties due to low levels of unsaturation, i.e. vinylgroups and/or oligomer content.

Examples

The following examples illustrate the present invention but are notintended to limit the scope of the invention.

Inventive Polyolefin Composition 1

Inventive polyolefin composition 1 (IPC-1) comprises an ethylene-octeneinterpolymer, having a density of approximately 0.954 g/cm³, a meltindex (I₂), measured at 190° C. and 2.16 kg, of approximately 2.6 g/10minutes, an melt flow ratio (I₁₀/I₂) of approximately 10. Additionalproperties of IPC-1 were measured, and are reported in Table 2.

IPC-1 was prepared via solution polymerization in adiabatic stirred tankreactors connected in parallel in the presence of a first catalystsystem, as described below, in the first reactor and a second catalystsystem, as described below, in the second reactor. First ethylenefraction and second ethylene fraction were contacted with each other andblended via solution blended process, and then followed withdevolatization and pelletization form IPC-1. The first catalyst systemcomprisesbis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethyl)-methylene-1,2-cyclohexanediylhafnium(IV) dimethyl, represented by the following formula:

The second catalyst system comprises((3-(2,7-di-tert-butyl-9H-carbazol-9-yl)-2′-(3-((3′-(2,7-di-tert-butyl-9H-carbazol-9-yl)-5-fluoro-2′-hydroxy-3-methyl-5′-(2,4,4-trimethylpentan-2-yl)-[1,1′-biphenyl]-2-yl)oxy)propoxy)-5′-fluoro-3′-methyl-5-(2,4,4-trimethylpentan-2-yl)-[1,1′-biphenyl]-2-yl)oxy)hafnium(IV) dimethyl, represented by the following formula:

The polymerization conditions for IPC-1 are reported in Table 1.Referring to Table 1, MMAO is modified methyl aluminoxane; and RIBS-2 isbis(hydrogenated tallow alkyl)methyl,tetrakis(pentafluorophenyl)borate(1-) amine, used as cocatalysts.

Inventive Polyolefin Composition 2

Inventive polyolefin composition 2 (IPC-2) comprises an ethylene-octeneinterpolymer, having a density of approximately 0.953 g/cm³, a meltindex (I₂), measured at 190° C. and 2.16 kg, of approximately 1.5 g/10minutes, an melt flow ratio (I₁₀/I₂) of approximately 9. Additionalproperties of IPC-2 were measured, and are reported in Table 2.

IPC-2 was prepared via solution polymerization in adiabatic stirred tankreactors connected in parallel in the presence of a first catalystsystem, as described below, in the first reactor and a second catalystsystem, as described below, in the second reactor. First ethylenefraction and second ethylene fraction were contacted with each other andblended via solution blended process, and then followed withdevolatization and pelletization form IPC-2.

The first catalyst system comprisesbis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethyl)-methylene-1,2-cyclohexanediylhafnium(IV) dimethyl, represented by the following formula:

The second catalyst system comprises((3-(2,7-di-tert-butyl-9H-carbazol-9-yl)-2′-(3-((3′-(2,7-di-tert-butyl-9H-carbazol-9-yl)-5-fluoro-2′-hydroxy-3-methyl-5′-(2,4,4-trimethylpentan-2-yl)-[1,1′-biphenyl]-2-yl)oxy)propoxy)-5′-fluoro-3‘-methyl-5-(2,4,4-trimethylpentan-2-yl)-[1,1’-biphenyl]-2-yl)oxy)hafnium(IV) dimethyl, represented by the following formula:

The polymerization conditions for IPC-2 are reported in Table 1.Referring to Table 1, MMAO is modified methyl aluminoxane; and RIBS-2 isbis(hydrogenated tallow alkyl)methyl,tetrakis(pentafluorophenyl)borate(1-) amine, used as cocatalysts.

Comparative Polyolefin Composition 1

Comparative polyolefin composition 1 (CPC-1) comprises anethylene-hexene interpolymer, having a density of approximately 0.956g/cm³, a melt index (I₂), measured at 190° C. and 2.16 kg, ofapproximately 1.4 g/10 minutes, an melt flow ratio (I₁₀/I₂) ofapproximately 13. Additional properties of CPC-1 are reported in Table2. CPC-1 was prepared via gas phase polymerization in a fluidized beddual reactor system.

Comparative Polyolefin Composition 2

Comparative polyolefin composition 2 (CPC-2) comprises anethylene-hexene interpolymer, having a density of approximately 0.954g/cm³, a melt index (I₂), measured at 190° C. and 2.16 kg, ofapproximately 2.3 g/10 minutes, an melt flow ratio (I₁₀/I₂) ofapproximately 11. Additional properties of CPC-2 are reported in Table2. CPC-2 was prepared via gas phase polymerization in a fluidized bedreactor system.

Comparative Polyolefin Composition 3

Comparative polyolefin composition 3 (CPC-3) comprises an ethylene-basedpolymer having a density of approximately 0.954 g/cm³, a melt index(I₂), measured at 190° C. and 2.16 kg, of approximately 2.2 g/10minutes, an melt flow ratio (I₁₀/I₂) of approximately 8. Additionalproperties of CPC-3 are reported in Table 2.

TABLE 1 Reactor 2 Component of Sample IPC-1 IPC-1 IPC-2 ReactorConfiguration type dual single dual parallel parallel Reactor1 SolventFeed Flow kg/hr 15.8 16.1 Reactor1 Ethylene Feed Flow kg/hr 1.8 1.8Reactor1 Hydrogen Feed Flow Standard 330 369 mL/min Reactor1 1-OcteneFeed Flow kg/hr 0.17 0.10 Reactor1 Feed Temp ° C. 23.6 20.8 Reactor1Feed Solvent to Ethylene kg/kg 9.0 9.0 Ratio Reactor1 Temp ° C. 141 140Reactor1 Oilbath Temp ° C. 139 140 Reactor1 Catalyst Feed Conc mmol/kg0.1 0.1 Reactor1 Catalyst Feed Flow g/hr 49 44 Reactor1 CoCatalyst1 Typetype RIBS2 RIBS2 Reactor1 CoCatalyst1 Feed Conc mmol/kg 0.12 0.12Reactor1 CoCatalyst1 Feed Flow g/hr 62 57 Reactor1 CoCatalyst2 Type typeMMAO3 MMAO3 Reactor1 CoCatalyst2 Feed Conc mmol/kg 3 3 Reactor1CoCatalyst2 Feed Flow g/hr 50 100 Reactor1 FTnIR Ethylene g/L 15.2 15.1Concentration Reactor1 Ethylene Conversion % 73.4 75.1 Reactor1Viscosity cPa 380 353 Reactor2 Solvent Feed Flow kg/hr 12.65 12.7 9.27Reactor2 Ethylene Feed Flow kg/hr 2.8 2.8 2.1 Reactor2 Hydrogen FeedFlow Standard 800 800 700 mL/min Reactor2 1-Octene Feed Flow kg/hr 0 0 0Reactor2 Feed Temp ° C. 7.6 7.6 4.8 Reactor2 Feed Solvent to Ethylenekg/kg 4.5 4.5 4.5 Ratio Reactor2 Temp ° C. 200 199 200 Reactor2 OilbathTemp ° C. 191 192 191 Reactor2 Catalyst Conc mmol/kg 0.02 0.02 0.02Reactor2 Catalyst Feed Flow g/hr 24 30 23 Reactor2 CoCatalyst1 Type typeRIBS2 RIBS2 RIBS2 Reactor2 CoCatalyst1 Conc mmol/kg 0.03 0.03 0.03Reactor2 CoCatalyst1 Flow g/kg 24 30 23 Reactor2 CoCatalyst2 Type typeMMAO3 MMAO3 MMAO3 Reactor2 CoCatalyst2 Feed Conc mmol/kg 3 3 3 Reactor2CoCatalyst2 Feed Flow g/hr 40 40 40 Reactor2 FTnIR Ethylene g/L 7.7 7.98.0 Concentration Overall Ethylene Conversion % 93.1 92.5 92.8 Reactor2Viscosity cPa 28 31 25

TABLE 2 Property Test Method Units IPC-1 IPC-2 CPC-1 CPC-2 CPC-3 DensityASTM D792 g/cm³ 0.954 0.953 0.956 0.954 0.954 Method B I₂ ASTM D1238dg/min 2.6 1.5 1.4 2.3 2.2 I₁₀ ASTM D1238 dg/min 25.5 13.5 17.9 25.318.3 I₂₁ ASTM D1238 dg/min 117.6 60.9 93.4 111.1 66.8 I₁₀/I₂ 10 9 13 118 I₂₁/I₂ 46 40 67 48 30 M_(n) Conventional GPC 21,576 23,115 8,56111,724 11,693 M_(w) Conventional GPC 90,213 103,224 121,348 107,509106,732 M_(w)/M_(n) Conventional GPC 4.2 4.5 14.2 9.2 9.1 M_(z)Conventional GPC 279,083 303,753 636,554 530,446 490,096 Tm1 DSC ° C.131.3 131.2 130.7 131.1 131.7 Heat of Fusion DSC J/g 211 208 212 212 211Tc1 DSC ° C. 117.5 117.8 117.4 117.4 117.9 Heat of Cryst. DSC J/g 210210 214 213 212 Tan Delta 0.1 DMS N/A 17.4 12.0 5.3 7.5 8.4 radians persecond η* @ 0.1 rad/s DMS Pa · s 3,692 5,896 8,105 4,802 4,557 [η* @0.1(rad/s)]/ DMS 4.4 5.1 8.6 5.9 4.3 [η* @ 100 (rad/s)] Width at ½ CEF °C. 4.40 4.20 3.60 3.40 3.20 height Width at 1/10 CEF ° C. 15.0 8.0 13.211.0 7.8 height Standard CEF ° C. 5.41 4.49 9.44 8.80 8.26 DeviationHalf Height CEF 0.814 0.935 0.382 0.386 0.387 Width/Std. Dev. CDC CDC117 102 249 246 245 Vinyls/1000 C. IR Method Less than Less than 0.140.2 0.21 0.15 0.15 Oligomer Content GC ug/g 47 38 415 280 327 ESCR, 10%ASTM D1693-B h 274 242 169 67 23 Igepal, F50

Test Methods

Test methods include the following:

Density

Samples that are measured for density are prepared according to ASTMD4703. Measurements are made within one hour of sample pressing usingASTM D792, Method B.

Melt Index

Melt index (I₂) is measured in accordance with ASTM D1238, Condition190° C./2.16 kg, and is reported in grams eluted per 10 minutes. Meltflow rate (I₁₀) is measured in accordance with ASTM D1238, Condition190° C./10 kg, and is reported in grams eluted per 10 minutes.

Differential Scanning Calorimetry (DSC)

DSC can be used to measure the melting and crystallization behavior of apolymer over a wide range of temperature. For example, the TAInstruments Q1000 DSC, equipped with an RCS (refrigerated coolingsystem) and an autosampler is used to perform this analysis. Duringtesting, a nitrogen purge gas flow of 50 ml/min is used. Each sample ismelt pressed into a thin film at about 175° C.; the melted sample isthen air-cooled to room temperature (˜25° C.). A 3-10 mg, 6 mm diameterspecimen is extracted from the cooled polymer, weighed, placed in alight aluminum pan (ca 50 mg), and crimped shut. Analysis is thenperformed to determine its thermal properties.

The thermal behavior of the sample is determined by ramping the sampletemperature up and down to create a heat flow versus temperatureprofile. First, the sample is rapidly heated to 180° C. and heldisothermal for 3 minutes in order to remove its thermal history. Next,the sample is cooled to −40° C. at a 10° C./minute cooling rate and heldisothermal at −40° C. for 3 minutes. The sample is then heated to 150°C. (this is the “second heat” ramp) at a 10° C./minute heating rate. Thecooling and second heating curves are recorded. The cool curve isanalyzed by setting baseline endpoints from the beginning ofcrystallization to −20° C. The heat curve is analyzed by settingbaseline endpoints from −20° C. to the end of melt. The valuesdetermined are peak melting temperature (T_(m)), peak crystallizationtemperature (T_(c)), heat of fusion (H_(f)) in Joules per gram and heatof crystallization (J/g) using Equation 1.

The heat of fusion (H_(f)) and the peak melting temperature are reportedfrom the second heat curve. Peak crystallization temperature and heat ofcrystallization is determined from the cooling curve.

Dynamic Mechanical Spectroscopy (DMS) Frequency Sweep

Samples were compression-molded into 3 mm thick×25 mm diameter circularplaques at 177° C. for 5 minutes under 10 MPa pressure in air. Thesample was then taken out of the press and placed on the counter tocool.

Constant temperature frequency sweep measurements were performed on anARES strain controlled rheometer (TA Instruments) equipped with 25 mmparallel plates, under a nitrogen purge. For each measurement, therheometer was thermally equilibrated for at least 30 minutes prior tozeroing the gap. The sample was placed on the plate and allowed to meltfor five minutes at 190° C. The plates were then closed to 2 mm, thesample trimmed, and then the test was started. The method has anadditional five minute delay built in, to allow for temperatureequilibrium. The experiments were performed at 190° C. over a frequencyrange of 0.1-100 rad/s at five points per decade interval. The strainamplitude was constant at 10%. The stress response was analyzed in termsof amplitude and phase, from which the storage modulus (G′), lossmodulus (G″), complex modulus (G*), dynamic complex viscosity (η*), andtan (δ) or tan delta were calculated.

Conventional Gel Permeation Chromatography (GPC)

The GPC system consists of either a Polymer Laboratories Model PL-210 ora Polymer Laboratories Model PL-220 instrument equipped with arefractive index (RI) concentration detector. The column and carouselcompartments are operated at 140° C. Three Polymer Laboratories 10-μmMixed-B columns are used with the solvent 1,2,4-trichlorobenzene. Thesamples are prepared at a concentration of 0.1 g of polymer in 50milliliters of solvent. The solvent used to prepare the samples contains200 ppm of the antioxidant butylated hydroxytoluene (BHT). Samples areprepared by agitating lightly for four hours at 160° C. The injectionvolume used is 200 microliters and the flow rate is 1.0 ml/min.Calibration of the GPC column set is performed with twenty one narrowmolecular weight distribution polystyrene standards purchased fromPolymer Laboratories.

The polystyrene standard peak molecular weights (M_(PS)) are convertedto polyethylene molecular weight (M_(PE)) using Equation 1. The equationis described in Williams and Ward, J. Polym. Sci., Polym. Letters, 6,621 (1968)):

M _(PE) =A×(M _(PS))^(B)  Equation 1

Where A has a value of 0.4316 and B is equal to 1.0.

A third order polynomial is determined to build the logarithmicmolecular weight calibration as a function of elution volume.

Polyethylene equivalent molecular weight calculations were performedusing PolymerChar “GPC One” software. The number average molecularweight (Mn), weight average molecular weight (Mw), and z-averagemolecular weight (Mz) was calculated by inputting the GPC results inequations 2 to 4:

$\begin{matrix}{\overset{\_}{Mn} = \frac{\sum\limits^{i}\; {RI}_{i}}{\sum\limits^{i}\; \left( \frac{{RI}_{i}}{M_{{PE},i}} \right)}} & {{Equation}\mspace{14mu} 2} \\{\overset{\_}{Mw} = \frac{\sum\limits^{i}\; \left( {{RI}_{i}*M_{{PE},i}} \right)}{\sum\limits^{i}\; {RI}_{i}}} & {{Equation}\mspace{14mu} 3} \\{\overset{\_}{Mz} = \frac{\sum\limits^{i}\; \left( {{RI}_{i}*M_{{PE},i}^{2}} \right)}{\sum\limits^{i}\; \left( {{RI}_{i}*M_{{PE},i}} \right)}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

Where RI_(i) and M_(PE,i) are the concentration detector baselinecorrected response and conventional calibrated polyethylene molecularweight for the i^(th) slice of the concentration response, elutionvolume paired data set. The precision of the weight-average molecularweight ΔMw is <2.6%.

The MWD is expressed as the weight average molecular weight (Mw) dividedby the number average molecular weight (Mn).

The GPC column set is calibrated by running 21 narrow molecular weightdistribution polystyrene standards. The molecular weight (MW) of thestandards ranges from 580 to 8,400,000, and the standards are containedin 6 “cocktail” mixtures. Each standard mixture has at least a decade ofseparation between individual molecular weights. The standard mixturesare purchased from Polymer Laboratories. The polystyrene standards areprepared at 0.025 g in 50 mL of solvent for molecular weights equal toor greater than 1,000,000 and 0.05 g in 50 mL of solvent for molecularweights less than 1,000,000. The polystyrene standards were dissolved at80° C. with gentle agitation for 30 minutes. The narrow standardsmixtures are run first and in order of decreasing highest molecularweight component to minimize degradation.

CEF Method

Comonomer distribution analysis is performed with CrystallizationElution Fractionation (CEF) (PolymerChar in Spain, (B Monrabal et al,Macromol. Symp., 257, 71-79,2007). Ortho-dichlorobenzene (ODCB) with 600ppm antioxidant butylated hydroxytoluene (BHT) is used as solvent.Sample preparation is done with auto sampler at 160° C. for 2 hoursunder shaking at 4 mg/ml (unless otherwise specified). The injectionvolume is 300 μl. The temperature profile of CEF is: crystallization at3° C./min from 110° C. to 30° C., the thermal equilibrium at 30° C. for5 minutes, elution at 3° C./min from 30° C. to 140° C. The flow rateduring crystallization is at 0.052 ml/min. The flow rate during elutionis at 0.50 ml/min. The data is collected at one data point/second.

CEF column is packed by the Dow Chemical Company with glass beads at 125μm±6% (MO-SCI Specialty Products) with ⅛ inch stainless tubing. Glassbeads are acid washed by MO-SCI Specialty with the request from the DowChemical Company. Column volume is 2.06 ml. Column temperaturecalibration is performed by using a mixture of NIST Standard ReferenceMaterial Linear polyethylene 1475a (1.0 mg/ml), and Eicosane (2 mg/ml)in ODCB. Temperature is calibrated by adjusting elution heating rate sothat NIST linear polyethylene 1475a has a peak temperature at 101.0° C.,and Eicosane has a peak temperature of 30.0° C. The CEF columnresolution is calculated with a mixture of NIST linear polyethylene1475a (1.0 mg/ml) and hexacontane (Fluka, purum, ≧97.0%, 1 mg/ml). Abaseline separation of hexacontane and NIST polyethylene 1475a isachieved. The area of hexacontane (from 35.0 to 67.0° C.) to the area ofNIST 1475a from 67.0 to 110.0° C. is 50 to 50, the amount of solublefraction below 35.0° C. is <1.8 wt %. The CEF column resolution isdefined in equation 1, where the column resolution is 6.0.

$\begin{matrix}{{Resolution} = \frac{\begin{matrix}{{{Peak}\mspace{14mu} {temperature}\mspace{14mu} {of}\mspace{14mu} {NIST}\mspace{14mu} 1475\; a} -} \\{{Peak}\mspace{14mu} {Temperature}\mspace{14mu} {of}\mspace{14mu} {Hexacontane}}\end{matrix}}{\begin{matrix}{{{Half}\text{-}{height}\mspace{14mu} {Width}\mspace{14mu} {of}\mspace{14mu} {NIST}\mspace{14mu} 1475\; a} +} \\{{Half}\text{-}{height}\mspace{14mu} {Width}\mspace{14mu} {of}\mspace{14mu} {Hexacontane}}\end{matrix}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Determination of Half Height and One Tenth Height of the CEF ElutionProfile

The CEF instrument is calibrated according to the CEF Method describedherein, and a plot of the relative IR detector signal is made as afunction of temperature. A single baseline is subtracted from the IRmeasurement signal in order create a relative mass-elution profile plotstarting and ending at zero relative mass at its lowest and highestelution temperatures (typically between 25° C. and 110° C.). Forconvenience, this plot (FIG. 1) plotted as a normalized quantity with anarea equivalent to 100. In the relative mass-elution profile plot, peaksthat represent an area of at least 25% of the total integrated signalbetween 35° C. and 110° C. degrees are assigned. Any peaks that do notreturn to the baseline by at least 10% of the relative mass-elutionheight (connected by more than 10% height at their lowest point), aredefined as a single peak (no deconvolution or similar numerical methodsare used to mathematically separate convoluted peaks). Each separatepeak is then measured for width in ° C. at 50% of the maximum height ofthe peak in the mass-elution profile plot. Each separate peak is thenmeasured for width ° C. at 10% of the maximum height in the mass-elutionprofile plot.

CDC Method

Comonomer distribution constant (CDC) is calculated from comonomerdistribution profile by CEF. CDC is defined as Comonomer DistributionIndex divided by Comonomer Distribution Shape Factor multiplying by 100as shown in Equation 1.

$\begin{matrix}{{CDC} = {\frac{{Comonomer}\mspace{14mu} {Distrubution}\mspace{14mu} {Index}}{{Comonomer}\mspace{14mu} {Distribution}\mspace{14mu} {Shape}\mspace{14mu} {Factor}} = {\frac{{Comonomer}\mspace{14mu} {Distribution}\mspace{14mu} {Index}}{{Half}\mspace{14mu} {{Width}/{Stdev}}}*100}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Comonomer distribution index stands for the total weight fraction ofpolymer chains with the comonomer content ranging from 0.5 of mediancomonomer content (C_(median)) and 1.5 of C_(median) from 35.0 to 119.0°C. Comonomer Distribution Shape Factor is defined as a ratio of the halfwidth of comonomer distribution profile divided by the standarddeviation of comonomer distribution profile from the peak temperature(T_(p)).

CDC is calculated from comonomer distribution profile by CEF, and CDC isdefined as Comonomer Distribution Index divided by ComonomerDistribution Shape Factor multiplying by 100 as shown in Equation 4, andwherein Comonomer distribution index stands for the total weightfraction of polymer chains with the comonomer content ranging from 0.5of median comonomer content (C_(median)) and 1.5 of C_(median) from 35.0to 119.0° C., and wherein Comonomer Distribution Shape Factor is definedas a ratio of the half width of comonomer distribution profile dividedby the standard deviation of comonomer distribution profile from thepeak temperature (Tp).

CDC is calculated according to the following steps:

(A) Obtain a weight fraction at each temperature (T) (w_(T)(T)) from35.0° C. to 119.0° C. with a temperature step increase of 0.2° C. fromCEF according to Equation 2.

$\begin{matrix}{{\int_{35}^{119.0}{{w_{T}(T)}\ {T}}} = 1} & {{Equation}\mspace{14mu} 2}\end{matrix}$

(B) Calculate the median temperature (T_(median)) at cumulative weightfraction of 0.500, according to Equation 3.

$\begin{matrix}{{\int_{35}^{T_{median}}{{w_{T}(T)}\ {T}}} = 0.5} & {{Equation}\mspace{14mu} 3}\end{matrix}$

(C) Calculate the corresponding median comonomer content in mole %(C_(median)) at the median temperature (T_(median)) by using comonomercontent calibration curve according to Equation 4.

$\begin{matrix}{{{\ln \left( {1 - {comonomercontent}} \right)} = {{- \frac{207.26}{273.12 + T}} + 0.5533}}{R^{2} = 0.997}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

(D) Construct a comonomer content calibration curve by using a series ofreference materials with known amount of comonomer content, i.e., elevenreference materials with narrow comonomer distribution (mono-modalcomonomer distribution in CEF from 35.0 to 119.0° C.) with weightaverage Mw of 35,000 to 115,000 (measured via conventional GPC) at acomonomer content ranging from 0.0 mole % to 7.0 mole % are analyzedwith CEF at the same experimental conditions specified in CEFexperimental sections;

(E) Calculate comonomer content calibration by using the peaktemperature (T_(p)) of each reference material and its comonomercontent. The calibration is calculated from each reference material asshown in Equation 4 wherein: R² is the correlation constant.

(F) Calculate Comonomer Distribution Index from the total weightfraction with a comonomer content ranging from 0.5*C_(median) to1.5*C_(median), and if T_(median) is higher than 98.0° C., ComonomerDistribution Index is defined as 0.95.

(G) Obtain Maximum peak height from CEF comonomer distribution profileby searching each data point for the highest peak from 35.0° C. to119.0° C. (if the two peaks are identical, then the lower temperaturepeak is selected); half width is defined as the temperature differencebetween the front temperature and the rear temperature at the half ofthe maximum peak height, the front temperature at the half of themaximum peak is searched forward from 35.0° C., while the reartemperature at the half of the maximum peak is searched backward from119.0° C., in the case of a well defined bimodal distribution where thedifference in the peak temperatures is equal to or greater than the 1.1times of the sum of half width of each peak, the half width of theinventive ethylene-based polymer composition is calculated as thearithmetic average of the half width of each peak; and

(H) Calculate the standard deviation of temperature (Stdev) accordingEquation 5

$\begin{matrix}{{Stdev} = \sqrt{\sum\limits_{35.0}^{119.0}\; {\left( {T - T_{p}} \right)^{2}*{w_{T}(T)}}}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

Creep Zero Shear Viscosity Measurement Method

Zero-shear viscosities are obtained via creep tests that were conductedon an AR-G2 stress controlled rheometer (TA Instruments; New Castle,Del.) using 25-mm-diameter parallel plates at 190° C. The rheometer ovenis set to test temperature for at least 30 minutes prior to zeroingfixtures. At the testing temperature a compression molded sample disk isinserted between the plates and allowed to come to equilibrium for 5minutes. The upper plate is then lowered down to 50 μm above the desiredtesting gap (1.5 mm). Any superfluous material is trimmed off and theupper plate is lowered to the desired gap. Measurements are done undernitrogen purging at a flow rate of 5 L/min. Default creep time is setfor 2 hours.

A constant low shear stress of 20 Pa is applied for all of the samplesto ensure that the steady state shear rate is low enough to be in theNewtonian region. The resulting steady state shear rates are in therange of 10⁻³ to 10⁻⁴ s⁻¹ for the samples in this study. Steady state isdetermined by taking a linear regression for all the data in the last10% time window of the plot of log (J(t)) vs. log(t), where J(t) iscreep compliance and t is creep time. If the slope of the linearregression is greater than 0.97, steady state is considered to bereached, then the creep test is stopped. In all cases in this study theslope meets the criterion within 2 hours. The steady state shear rate isdetermined from the slope of the linear regression of all of the datapoints in the last 10% time window of the plot of E vs. t, where e isstrain. The zero-shear viscosity is determined from the ratio of theapplied stress to the steady state shear rate.

In order to determine if the sample is degraded during the creep test, asmall amplitude oscillatory shear test is conducted before and after thecreep test on the same specimen from 0.1 to 100 rad/s. The complexviscosity values of the two tests are compared. If the difference of theviscosity values at 0.1 rad/s is greater than 5%, the sample isconsidered to have degraded during the creep test, and the result isdiscarded.

Zero-Shear Viscosity Ratio (ZSVR) is defined as the ratio of thezero-shear viscosity (ZSV) of the branched polyethylene material to theZSV of the linear polyethylene material at the equivalent weight averagemolecular weight (Mw-gpc) according to the following Equations 1 and 2

$\begin{matrix}{{ZSVR} = \frac{\eta_{0\; B}}{\eta_{0\; L}}} & {{Equation}\mspace{14mu} 1} \\{\eta_{0\; L} = {2.29 \times 10^{- 15}M_{w - {gpe}}^{3.65}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

The ZSV value is obtained from creep test at 190° C. via the methoddescribed above. The Mw-gpc value is determined by the conventional GPCmethod (Equation 3). The correlation between ZSV of linear polyethyleneand its Mw-gpc was established based on a series of linear polyethylenereference materials. A description for the ZSV-Mw relationship can befound in the ANTEC proceeding: Karjala, Teresa P., Sammler, Robert L.,Mangnus, Marc A., Hazlitt, Lonnie G., Johnson, Mark S., Hagen, CharlesM. Jr., Huang, Joe W. L., Reichek, Kenneth N., “Detection of low levelsof long-chain branching in polyolefins”, Annual TechnicalConference—Society of Plastics Engineers (2008), 66th 887-891.

¹H NMR Method

3.26 g of stock solution is added to 0.133 g of polyolefin sample in 10mm NMR tube.

The stock solution is a mixture of tetrachloroethane-d₂ (TCE) andperchloroethylene (50:50, w:w) with 0.001M Cr³⁺. The solution in thetube is purged with N₂ for 5 minutes to reduce the amount of oxygen. Thecapped sample tube is left at room temperature overnight to swell thepolymer sample. The sample is dissolved at 110° C. with shaking. Thesamples are free of the additives that may contribute to unsaturation,e.g. slip agents such as erucamide.

The ¹H NMR are run with a 10 mm cryoprobe at 120° C. on Bruker AVANCE400 MHz spectrometer.

Two experiments are run to get the unsaturation: the control and thedouble presaturation experiments.

For the control experiment, the data is processed with exponentialwindow function with LB=1 Hz, baseline was corrected from 7 to −2 ppm.The signal from residual ¹H of TCE is set to 100, the integral I_(total)from −0.5 to 3 ppm is used as the signal from whole polymer in thecontrol experiment. The number of CH₂ group, NCH₂, in the polymer iscalculated as following:

NCH₂ =I _(total)/2  Equation 1

For the double presaturation experiment, the data is processed withexponential window function with LB=1 Hz, baseline was corrected from6.6 to 4.5 ppm. The signal from residual ₁H of TCE is set to 100, thecorresponding integrals for unsaturations (I_(vinylene),I_(trisubstituted), I_(vinyl) and I_(vinylidene)) were integrated basedon the region shown in FIG. 6. The number of unsaturation unit forvinylene, trisubstituted, vinyl and vinylidene are calculated:

N _(vinylene) =I _(vinylene)/2  Equation 2

N _(trisubstituted) =I _(trisubstitute)  Equation 3

N _(vinyl) =I _(vinyl)/2  Equation 4

N _(vinylidene) =I _(vinylidene/)2  Equation 5

The unsaturation unit/1,000 carbons are calculated as following:

N _(vinylene)/1,000C=(N _(vinylene)/NCH₂)*1,000  Equation 6

N _(trisubstituted)/1,000C=(N _(trisubstituted)/NCH₂)*1,000  Equation 7

N _(vinyl)/1,000C=(N _(vinyl)/NCH₂)*1,000  Equation 8

N _(vinylidene)/1,000C=(N _(vinylidene)/NCH₂)*1,000  Equation 9

The chemical shift reference is set at 6.0 ppm for the ¹H signal fromresidual proton from TCT-d2. The control is run with ZG pulse, TD 32768,NS 4, DS 12, SWH 10,000 Hz, AQ 1.64 s, D1 14 s. The double presaturationexperiment is run with a modified pulse sequence, O1P 1.354 ppm, O2P0.960 ppm, PL9 57 db, PL21 70 db, TD 32768, NS 200, DS 4, SWH 10,000 Hz,AQ 1.64 s, D1 1 s, D13 13s.

¹³C NMR Method

The samples were prepared by adding approximately 2.74 g oftetrachloroethane-d₂ containing 0.025 M Cr (AcAc)₃ to 0.2 g sample in aNorell 1001-7 10 mm NMR tube. Oxygen was removed by manually purgingtubes with nitrogen using a Pasteur pipette for 1 minute. The sampleswere dissolved and homogenized by heating the tube and its contents to˜150° C. using a heating block with minimal use of heat gun. Each samplewas visually inspected to ensure homogeneity. Samples were thoroughlymixed immediately prior to analysis, and were not allowed to cool beforeinsertion into the heated NMR probe. This is necessary to ensure thesample is homogeneous and representative of the whole. The data werecollected using a Bruker 400 MHz spectrometer equipped with a Brukercryoprobe. The data were acquired using 160 scans, a 6 sec pulserepetition delay with a sample temperature of 120° C. All measurementswere made on non-spinning samples in locked mode. Samples were allowedto thermally equilibrate for 7 minutes prior to data acquisition. The¹³C NMR chemical shifts were internally referenced to the EEE triad at30 ppm.

Oligomers in PE Using GC

About 5 grams of sample is weighed and transferred to a glass bottle. Apipette is used to deliver 20 mL of methylene chloride to the glassbottle. The bottle is capped with a Teflon lined lid and the contentsare shaken for 24 hours at room temperature. After extraction an aliquotof methylene chloride is removed and placed into a GC autosampler vial.The sample extracts are analyzed by GC with a flame ionization detectoralong with a hydrocarbon standard. Total peak area is determined forpeaks between methylene chloride and C44H90. The peaks for Irgafos 168,oxidized I-168 and Irganox 1076 are excluded. The concentration in partsper million is calculated including the range from C₁₀-C₄₄ using anexternal standard calibration with a C20H42 calibration standard.

Vinyls, and Unsaturation Determination by IR Method

Pellets are pressed into a film and film is analyzed by FTIR todetermine concentration of each in sample. Results are reported as thenumber per 1000 carbons. Procedures were conducted as per ASTM D6248Standard Test Method for Vinyl and Trans Unsaturation in Polyethylene byInfrared Spectrophotometry.

We claim:
 1. A polyolefin composition suitable for injection moldingapplications comprising: an ethylene/α-olefin interpolymer compositioncomprising: (a) from 25 to 50 percent by weight of a firstethylene/α-olefin copolymer fraction having a density in the range offrom 0.924 to 0.937 g/cm³, a melt index (I₂) in the range of from 0.03to 0.3 g/10 min, (b) from 50 to 75 percent by weight of a secondethylene homopolymer fraction having a density in the range of fromgreater than 0.960 g/cm³, a melt index (I₂) in the range of from 100 to180 g/10 minutes, wherein said ethylene/α-olefin interpolymercomposition has a density in the range of from 0.950 to 0.958 g/cm³, amelt index (I₂) in the range of from 1.0 g/10 min to 3.5 g/10 min, azero shear viscosity ratio (ZSVR) in the range of from 1.01 to 2.5, amolecular weight distribution (M_(w)/M_(n)) in the range of from 2.0 to4.0, and tan delta at 0.1 radian/second and 190° C. in the range of from9 to 50, wherein said ethylene/α-olefin interpolymer composition has atleast 1 peak on elution profile via crystallization elutionfractionation (CEF) procedure, wherein said peak comprises at least 95weight percent of the total area of the elution profile, wherein saidelution temperature peak is at an elution temperature greater than 95°C., and wherein the width of the elution temperature peak at 50 percentpeak height is greater than 4° C. and less than 6° C., and wherein thestandard deviation of the temperature is less than 6° C.
 2. Thepolyolefin composition of claim 1, wherein said ethylene/α-olefininterpolymer composition characterized by one or more of the followings:a. has a vinyl unsaturation of less than 0.15 vinyls per one thousandcarbon atoms present in the backbone of the ethylene/α-olefininterpolymer composition; and/or b. has a tan delta at 0.1radian/second, determined at 190° C., in the range of from 9 to 50; c.has CDC in the range of from 150 or less; d. has a ESCR F50 failure timeof at least 150 hours, as determined by ASTM 1693 Method B in 10%aqueous Igepal; and/or e. has a oligomer, i.e. C₁₀ to C₄₄, content ofless than 100 ppm.
 3. The polyolefin composition of claim 1 furthercomprising one or more ethylene polymers, or one or more propylene basedpolymers, or combinations thereof.
 4. A closure device comprising thepolyolefin composition of claim 1.